Porous metal filter element



renews 1m mink 1 MENcr a 1 w s 11. Davis; Dayton; Ohio, si'glio'r tiong becom more or less clogged with 1 solid pa clesit is; diilicult to remote suchsolidi arti'ci s dueto the relativeweakness and easy estructibility o i'u such non-'metallimfilter e metallic filter. elements "of this invention may be." cleansed of some ind '6 fm tfl e "to form a highly porousrigid metal-sheet of an orjeign particles by the chemical action at a suit able temperatureo'f chosengasesor liquids which will attack the nonrmetallic particles but will not attack ithernetal structure of? the "filter element. :In these respects a metallic filter element made tgMi faceiof a graphite m v layer ;of substantial'-"depth.. lz'l 'h'e top of the ipow- -de1 is" scrapped ofl to i a smooth level surfaceby any suitable means topiorm a loose uncom pacted layer of 'powder'having' the de' de for example 5; inch deep, "Themoid ran pacted powder layerl thereon is then; heated in non oxidizing or reducing atm'osphereflinasjuih .7 able furnace at a temperatureaof 2025,1510; a shorttime about 8 minutes) to cause'theni'ckel V and .copperparticles 'to alley or' sinter together alloy having'Monel-metal composition and vrhi will; resist corrosion to a highdegree fAiter this sintering step is completed; the porous; metal sheet is cooled ina non-oxidizing or. reducing 'mosphere and then readily lifted from the jhar according to this invention has distinct advantagesoyer previously known non-metallic filte'rs. Furtherfadvant'ag'es of .the filter elements of V thisinyention'overlmown flexible formsof-fllten 4o elements'are' j "(1-) --Gre "er ength and rigidityjto sustain the" H I pressur of the liquid'being filtered; v

(2) Gr eater unifQrmityin degree of porosityor ,finness'of pores; I p (3 Economy of nianuiiacture of a large-m mber .ot filter elements .all having the same; de-. 'gree ofporosity. V H a .u. v Q( 4)I Economy of'manuia'cture of a ,metallic fllteri s q f g" i u pe d "I50 element of anya suitable metals 'orlm'etal er me V "alloys so that themetal of the-.-fllter*ele-" 7 "ment will not; ,-cont'am inate the liquid vbe-,

.' in'gfilteredf or will not be corrodedf'by the liquid being filtered. v

graphite surface upon which it lay during sinte ing. This-resultsin a highly. porousmetal me brane which may be ter element;

'd'e'sc'ri large I pores therethroughto more free the' passage of liquid therethrough' If th particles are so smalfasfto pass mesh screen the finalpor'ous mem ra eiwill obiects andfadyanta gsb; .tn br'seat sired metal alloy in the final porous membrane, in each case the sintering temperature used be ing such as will cause the metal powders being used to alloy or sinter together without such melting as will destroy the high porosity of the final metal structure. In order. to provide a highly porous bronzemembrane any desired proportions of copper and tin metal powders may be used in the process described above. For instance from about 90% to about 97% copper powder may be used with from 10% to 3% of tin powder. The sintering temperature for coppertin mixtures is preferably quite close'to 1500 F.

If desired, the highly porous metal membrane made by the process described above may be somewhat compacted after the sintering step to control its porosity or density. This is prefer ably done by passing the highly porous membrane between pressure rolls or by any. other suitable compression method. Obviously the degree of porosity of the' highlyporousmetal membrane may be reduced as much or as little'as desired by such rolling of the porous metal structure. I

Porous metal membranes having a very high degree of uniformity of porosity may be rapidly and very economically made by the method of this invention. Such membranes may be used in general -for filtering foreign'matter from a liquid or from a gas or air where the-size of the foreign particles are'very minute; As examples,

they may be used in filters for the refrigerant in household refrigerators, oil filters in automobile engines, gasoline filters, etc. r

.While'the embodiment of the present inven tion as herein, disclosed, constitutes a preferred form, it is to be understood that other forms constituents of the alloy in a non-compacted intimately mixed condition.

2. A filter element comprising a relatively'wide thin highly porous sheet of a homogeneous alloy of copper. and nickel powders, said alloy being formed by sintering a thin layer of intimately mixed non-compacted copper and nickel powders.

3. A filter element comprising a thin highly porous sheet of a homogeneous bronze alloy hav- 7 .ing suflicient porosity to permit a liquid to freely pass therethrough, said alloy being formed by sintering together a thin layer of intimately mixed non-compacted copper and tin powders.

4. A filter element comprising a thin highly poroussheet of bronze having sufiicient porosity to permit free fluid flow therethrough, said bronze having an analysis wherein copper is present in the range of from 90 to 97% and wherein tin is presentin the'r'ange of from 10 to3%. y

5. A filter'jelement comprising a relatively thin highly porous sheet of a" homogeneous alloy having sufiicient porosity to permit liquid to" freely pass therethrough. said sheet being formed by sintering together a substantially uniform layer of metal powder in the loose noncompacted condition upon a nonadhering supporting surface. JAMES H. DAVIS. 

